Fluid systems transport materials and chemicals and perform work, such as powering downhole tools with hydraulics, during drilling and production operations for oil and gas. Fracturing fluids are the fluids pumped into the wellbore with a proppant in order to fracture a rock formation. A high pressure injection of fracturing fluid at a target depth creates cracks in rock formation, and the fracturing fluid enters these cracks. The proppant, such as sand or other particulates, prevent the cracks from closing when the pressured injection of fluid stops. The fracture is held open by the proppant so that the formation remains permeable by oil, gas, salt water, and other fluids, which can now be pumped through the well. Drilling fluid, also known as drilling mud, lubricates and transports materials, during drilling operations. The drilling fluid is pumped from the surface, usually a mud pit, to the wellbore with additives, such as coolants and stabilizers. Drilling fluid carries drill cuttings from the wellbore to the surface, cools the drill bit, and provides hydrostatic pressure so that fluids from the rock formation do not enter the wellbore. Drilling fluids can also be used to suspend the drill cuttings in the drilling mud, when the drill bit stops. The pulverized rock at the drill bit can be suspended in the drilling mud and pumped back out of the borehole for removal. There can be other functions of drilling fluids, including hydraulic energy for downhole tools and pulse telemetry for transmitting information through the wellbore. Drilling fluids are selected for the particular work to be done by the fluid, conditions of the wellbore, and ability to limit corrosion and damage to the formation.
Categories of drilling fluids include water based muds, and oil based muds. Water based muds are free flowing, when being pumped. At rest, the water based mud gels in order to suspect drill cuttings and resist pumping. Additional pumping force is needed in order to break the gel and restart pumping in the free flowing condition. The water and clay are the basic components, and various additives can be included in the fluid system for viscosity, coolant, and lubrication control. Oil based mud contains a petroleum product, such as diesel fuel, as the free flowing fluid component. There is increased lubricity and less viscosity for these oil based fluid systems. Furthermore, the oil based drilling fluid systems withstand greater heat without degradation. There are additional environmental concerns and issues with analyzing the drill cuttings transported by oil based mud. The oil and water are the basic components, and various additives must be included in order to maintain the dispersion of water, as a contaminant, in the fluid. Emulsifiers, wetting agents, and gellants can be used to control stability, viscosity, coolant, and lubrication of an oil based drilling fluid system. Stability of the oil based drilling fluid systems relates to preventing the separation of the fluid into two layers, the oil and the water.
With advances in drilling to greater depths, wellbore conditions are more extreme. The drilling fluid systems must tolerate the more difficult conditions. Oil based drilling fluid systems are being used to withstand the high pressure and high temperature conditions at these greater depths. Water based drilling fluid systems do not work at the elevated pressures and temperatures of these more extreme wellbore conditions. With deeper wells, the need for oil based drilling fluid systems has expanded, and the demands for more stable oil based drilling fluid systems is greater.
The prior art discloses oil based drilling fluid systems with selected additives to control stability, viscosity, coolant, and lubrication.
U.S. Pat. No. 5,593,953, issued to Malchow Jr. on 14 Jan. 1997, identifies an oil based drilling fluid with a need to emulsify the brine or contaminated water in order to lower viscosity. The additive is specified as a friction modifier, and the particular chemical formula is provided. U.S. Pat. No. 8,969,261, issued to Talingting Pabalan et al. on 3 Mar. 2015, discloses ingredients of a composition for changing viscosity of a solution. The particular composition can be added to various solutions, not just drilling fluids to affect rheology of a solution.
However, the prior art references do not relate to the same material composition, and the prior art with similar ingredients are not related to the same drilling fluids. There is no disclosure of emulsifiers for drilling fluid systems in high density and high temperature conditions, and in particular emulsifiers with nitrogen based components with stability in the high density and high temperature conditions.
U.S. Pat. No. 6,620,770, issued to Kirsner et al. on 16 Sep. 2003, also identifies an oil based drilling fluid with an emulsifier based on polyamides, a nitrogen based component. The polyamides are one additive in a composition to emulsify the oil based drilling fluid, wherein the emulsifier is reacted before being added to the drilling fluid. The emulsifier is not related to high density and high temperature conditions. Furthermore, prior art also teaches against the use of nitrogen based emulsifiers in the high temperature conditions. US Patent Publication No. 2011/0166047, published on 7 Jul. 2011 for Patel et al. discloses a nitrogen-free emulsifying agent.
It is an object of the present invention to provide an oil based drilling fluid system for high density and high temperature conditions.
It is another object of the present invention to provide an oil based drilling fluid system for a temperature range of 150-260 degrees Celsius.
It is another object of the present invention to provide an oil based drilling fluid system for a density range of specific gravity (SG) range of 2.0-2.8.
It is another object of the present invention to provide an oil based drilling fluid system for deeper wells with wellbore conditions that require high density drilling fluids in high temperature conditions.
It is an object of the present invention to provide an oil based drilling fluid system having an emulsifier of nitrogen based components with stability at high density and high temperatures.
It is another object of the present invention to provide an oil based drilling fluid system having an emulsifier of a mixture of polymeric amides or polyamides.
It is still another object of the present invention to provide an oil based drilling fluid system having an emulsifier of a mixture of polyamides derived from a fatty oil, diethylenetriamine, and maleic acid.
It is an object of the present invention to provide a method of manufacturing an emulsifier of an oil based drilling fluid system derived from a fatty oil, diethylenetriamine, and maleic acid.
It is another object of the present invention to provide a method of manufacturing an emulsifier of a mixture of polyamides derived from a fatty oil, diethylenetriamine, and maleic acid.
It is an object of the present invention to provide an oil based drilling fluid system having a biologically friendly emulsifier.
It is another object of the present invention to provide an oil based drilling fluid system having an emulsifier with less risk of environmental contamination.
These and other objectives and advantages of the present invention will become apparent from a reading of the attached specification.